A meta-analysis of two trials found it took patient treated with a sequence of martensitic-active copper-nickel-titanium (CuNiTi) slightly longer to reach the working archwire (MD: 0.54 months, 95% CI: -0.87 to 1.95) compared with a martensitic-stabilized NiTi sequence. However, patients treated with a sequence of martensitic-active CuNiTi archwires reported general greater pain intensity on the Likert scale 4 h and 1 day after placement of each archwire, compared with a martensitic-stabilized NiTi sequence

The authors concluded

There is insufficient data at present to make recommendations for the use of any available arch- wire type regarding effectiveness, efficacy, treatment outcome, or potential side effects. The meta-analyses conducted are limited by the small number of trials and methodological issues and must therefore be subsequently confirmed.

Comment

This review is one of a pair of review of orthodontic treatment conducted by the same group (Dental Elf 23rd May 2014). The Cochrane Oral Health Group has a review that has also assessed the effectiveness of initial archwires for orthodontic alignment (Jian et al 2013). The second update of that review was published last year. They only included 9 RCTs involving 571 patients and concluded

There is no reliable evidence from the trials included in this review that any specific initial arch wire material is better or worse than another with regard to speed of alignment or pain. There is no evidence at all about the effect of initial arch wire materials on the important adverse effect of root resorption.